1. Field of the Invention
The present invention relates to an interference preventing system for a construction machine having a multi-articulated front device, and more particularly to an interference preventing system for a hydraulic excavator having a front device including an arm, a boom, a bucket, an offset, etc., which prevents the front device from interfering with a vehicle body, in particular, a cab.
2. Description of the Related Art
A hydraulic excavator is operated by an operator manipulating front members such as a boom and so on with respective manual control levers. In a front device including an offset to provide a wide range of excavation, however, there is a risk that the front device may interfere with a vehicle body, in particular, a cab depending on its attitude.
Therefore, interference preventing system for preventing such an interference are described in JP-A-3-217523 and JP-B 6-104985.
According to the proposal of JP-A-3-217523, an interference between the front device and the cab can be prevented by stopping the operation of the front device when the tip end of the front device moves closer to the cab than respective planes set around the cab on the front side, the upper side and the lateral side.
According to the proposal of JP-B-6-104985, an interference between the front device and the cab can be prevented by, when the tip end of the front device moves closer to the cab than respective planes set around the cab on the front side, the upper side and the lateral side, automatically operating a boom cylinder, a bucket cylinder and a lateral shift cylinder (offset cylinder) so that the tip end of the front device goes to outside the set planes.